Cameras and other image recording devices often use one or more image sensors, such as a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor. When an image of a scene is captured, the scene can include objects that can be positioned or illuminated in a way that can make it difficult to represent the objects with acceptable detail. For example, an object in the scene can be positioned in a shadow, or the object can be illuminated by a bright light source, such as the sun.
The dynamic range of an image sensor quantifies the ability of the image sensor to adequately image both high light areas in a scene and low dark areas or shadows in the scene. In general, the dynamic range of an image sensor is less than that of the human eye. The limited dynamic range of an image sensor can result in an image losing details in the brighter areas or in the darker areas of the scene.
A variety of algorithms have been produced to improve the dynamic range of image sensors. One such algorithm varies the integration times (the time light is collected) of the pixels in the image sensor, which produces multiple images of a scene. For example, some pixels can have a shorter integration time while other pixels can have a longer integration time. The pixels with the shorter integration time can better capture the brighter areas in a scene and the pixels with the longer integration time can better capture darker areas in the scene. The charge or signals output from the pixels having the shorter and longer integration times can be combined to produce a final high dynamic range image that has more detail in the lighter and darker areas of the image.
However, when integration times of the pixels are varied, the final high dynamic range image can include undesirable motion artifacts. Since the final high dynamic range image is essentially a combination of two images, one image captured with the shorter integration time and another image captured with the longer integration time, objects in the scene can move in between the times the two images are captured. Thus, the scene represented in the image captured with the shorter integration time can differ from the scene represented in the image captured with the longer integration time. This difference can produce motion artifacts, such as blurring, in the combined final high dynamic range image.